首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1384265篇
  免费   128774篇
  国内免费   2505篇
  2021年   17990篇
  2019年   16260篇
  2018年   17741篇
  2017年   16357篇
  2016年   28168篇
  2015年   42694篇
  2014年   50848篇
  2013年   77049篇
  2012年   39087篇
  2011年   27707篇
  2010年   43879篇
  2009年   45295篇
  2008年   26131篇
  2007年   24119篇
  2006年   28926篇
  2005年   29931篇
  2004年   29174篇
  2003年   26652篇
  2002年   24599篇
  2001年   37933篇
  2000年   35246篇
  1999年   34089篇
  1998年   25954篇
  1997年   25810篇
  1996年   25272篇
  1995年   23357篇
  1994年   23192篇
  1993年   22333篇
  1992年   28797篇
  1991年   26901篇
  1990年   25519篇
  1989年   26290篇
  1988年   23973篇
  1987年   22785篇
  1986年   21523篇
  1985年   23172篇
  1984年   23021篇
  1983年   20351篇
  1982年   20781篇
  1981年   20006篇
  1980年   18639篇
  1979年   19137篇
  1978年   17860篇
  1977年   17183篇
  1976年   16408篇
  1975年   15707篇
  1974年   16181篇
  1973年   16503篇
  1972年   13868篇
  1971年   12829篇
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
291.
292.
293.
294.
295.
It has been suggested by some authors that the low fruit to flower ratio in some Proteaceae is due to andromonoecy, while others, looking particularly at Banksia , have not been able to find evidence for male flowers in the inflorescences. Stirlingia latifolia, Xylomelum occidentals and X. angustifolium are clearly andromonoecous, while no evidence for this condition could be found in Brabejum stellatifoliutn. Production of fertile fruit is related to andromonoecy in Xylomelum and S. latifolia but not in Brabejum. It is unlikely that all-encompassing solutions will be found to what initially seem to be widespread traits in the family, especially in regard to pollination biology, as the genera in the family occupy widely different environments and have very diverse ecological ranges.  相似文献   
296.
HbA1c is the most prevalent of the minor human hemoglobins. It is formed by the nonenzymatic addition of glucose to the alpha-amino group of the beta chain by an initial condensation reaction and a subsequent intermolecular Amadori rearrangement. We have developed a method of analysis which utilizes high performance liquid chromatography to follow the formation of HbA1c and greatly simplifies the determination of the kinetic parameters associated with this reaction. This has allowed us to study the effects of several Hb ligands, including the hydrogen ion, on the kinetics of this glycosylation reaction. Both the initial condensation reaction and the subsequent rearrangement are shown to exhibit acid catalysis, but the rate of the condensation step is limited by the extent of protonation of the alpha-amino group. The variation in kinetic parameters as a function of hydrogen ion concentration has allowed us to determine the probable reaction mechanism of HbA1c formation by comparison to previously reported model systems of Schiff base formation and Amadori rearrangement. The formation of pre-HbA1c from deoxy-Hb shows an increased forward rate when compared to oxy-Hb. The presence of physiologic concentrations of CO2 causes a proportional decrease in both k1 and k-1. 2,3-Diphosphoglycerate causes a significant increase in the keq of the formation reaction. The effects of CO and the substitution of L-glucose for D-glucose are not significant.  相似文献   
297.
Some points of CLIFF /KRUS 's important rotation procedure are criticized. This result in the definition of simple structure of canonical solutions, the use of STEWART /LOVE 's redundancy index as a measure of common variance, and two new rotation procedures (HAKSTIAN 's modified varimax rotation, separate rotation of both sets). The objects of rotation should be the (intraset) loadings.  相似文献   
298.
299.
A critical factor in clinical development of cancer immunotherapies is the identification of tumor-associated antigens that may be related to immunotherapy potency. In this study, protein microarrays containing >8,000 human proteins were screened with serum from prostate cancer patients (N = 13) before and after treatment with a granulocyte–macrophage colony-stimulating factor (GM-CSF)-secreting whole cell immunotherapy. Thirty-three proteins were identified that displayed significantly elevated (P ≤ 0.05) signals in post-treatment samples, including three proteins that have previously been associated with prostate carcinogenesis, galectin-8, T-cell alternative reading frame protein (TARP) and TNF-receptor-associated protein 1 (TRAP1). Expanded analysis of antibody induction in metastatic, castration-resistant prostate cancer (mCRPC) patients (N = 92) from two phase 1/2 trials of prostate cancer immunotherapy, G-9803 and G-0010, indicated a significant (P = 0.03) association of TARP antibody induction and median survival time (MST). Antibody induction to TARP was also significantly correlated (P = 0.036) with an increase in prostate-specific antigen doubling time (PSADT) in patients with a biochemical (PSA) recurrence following prostatectomy or radiation therapy (N = 19) from in a previous phase 1/2 trial of prostate cancer immunotherapy, G-9802. RNA and protein encoding TARP and TRAP1 was up-regulated in prostate cancer tissue compared to matched normal controls. These preliminary findings suggest that antibody induction to TARP may represent a possible biomarker for treatment response to GM-CSF secreting cellular immunotherapy in prostate cancer patients and demonstrates the utility of using protein microarrays for the high-throughput screening of patient-derived antibody responses.  相似文献   
300.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号